LONDON, ENGLAND - OCTOBER 29: Ashley Cole of Chelsea clashes with Arsenal goalkeeper Wojciech Szczesny during the Barclays Premier League match between Chelsea and Arsenal at Stamford Bridge on October 29, 2011 in London, England. (Photo by Clive Rose/Getty Images)
Considering the way Cole has been playing for most of the season I wouldn't be surprised if that ankle injury had been sustained over the summer. And that's only half-joking*. However poorly Cole's been playing, however, this isn't good news - dropping Ryan Bertrand straight into the fire because you're forced to isn't really the best way to introduce him to Premier League football.
*A Cole injury during the summer would explain both his terrible play and the out-of-nowhere Alvaro Pereira chase.
Also, remember when we had some Russian dude who could fill in at left back and left midfield? Good times.